Fully in Blueprints. I'm an experienced programmer but Blueprints have totally won me over. The only subsystem that I had to code was the connection to the socket chat server and I made it into a plugin so it's still being accessed from Blueprints.
Persistent storage of data in a mySQL database. Character position and stats are saved when the character logs off and restored when it enters world again.
No third-party solution (such as Photon or RakNet) required - so no monthly fees and you are free to host your server anywhere you want. I'm hosting the demo server on Softlayer and will provide detailed instructions on how to set up a server for those who are new to dedicated servers in general.
Registration, login and character creation.
Authoritative server
Launcher/autoupdater that can update the game and itself (separate application, in C#). Because you don't want to make your users download the full game over again after each minor update
Combat and targeting
Roaming and aggressive NPCs that fight back and chase after the player if attacked
